Localization of urokinase-type and tissue-type plasminogen activator mRNA during organogenesis in the mouse

Abstract

Cryostat sections of E8.5 to E9.5 mouse embryos were hybridized with S-labelled RNA probes to urokinase-type and tissue-type plasminogen activator (uPA and tPA, respectively) mRNA. The sections were screened for expression of either gene. Two main features emerge from the results. (a) The stage of initial detection is different for each transcript. The uPA mRNA is first detected in cephalic mesenchyme at E8.5 when tPA mRNA is already widely distributed in tissues derived from ectoderm and mesoderm; later, the uPA mRNA transcripts were found throughout most mesodermic tissues, (b) Each gene presents a different pattern of expression. The uPA is restricted to single cells or to small groups of cells within tissues; this distribution suggests its involvement in cell migratory mechanisms. On the other hand, tPA was detected in most tissues, with variable intensities. Its expression gains complexity while organogenesis proceeds. This pattern supports the hypothesis that regulatory mechanisms other than a direct gene regulation are involved. In extraembryonic tissues, uPA and tPA genes are constantly expressed at a high level in trophoblastic giant cells and parietal endoderm, respectively. Our results confirm the presence of plasminogen activator during embryonic development and provide detailed picture of the plasminogen activator gene expression in mouse organogenesis.

Transient expression of a novel serine protease in the ectoderm of the ascidian Herdmania momus during development

“…Plasminogen and its activators are associated with cell migration and tissue remodelling in processes such as neurogenesis and organogenesis, although the developmental expression is complex and not restricted to ectoderm-derived tissues (Moonen et al 1982;Menoud et al 1989;Sumi et al 1992). HGF is also expressed in a complex and changing pattern during development in neural, epithelial and mesodermal tissues, and has both mitogenic and cell scattering properties (reviewed in Warn 1994;Bronner-Fraser 1995).…”

Distribution of mRNA coding for Alpha-2-macroglobulin, the murinoglobulins, the Alpha-2-macroglobulin receptor and the Alpha-2-macroglobulin receptor associated protein during mouse embryogenesis and in adult tissues

“…The exact nature of this role needs to be further examined by delineation and identification of the ligands being bound. Apo E and lipoprotein lipase are not very likely to be necessary ligands, at least not for embryonic development, since mice homozygous for the disrupted apo E gene appear healthy [43] and humans who lack both copies of the gene for lipoprotein lipase develop normal-Other candidates are the tissue and urokinase plasminogen activators, which are expressed in the embryo during the first half of gestation [37,481. It needs to be demonstrated whether also PA11 is expressed during this period, since only tPA-or uPA-PA11 complexes are effectively recognized by the a,MR [40, 411.…”

Gene Manipulation and Transfer of the Plasminogen and Coagulation System in Mice

“…Evidence has been provided that the plasminogen system might be involved in brain function. Fibrinolytic system components are expressed in specialized areas of the brain during development 112 or in adulthood following different forms of brain activity. 113,114 In addition, in vitro studies with cultured neurons revealed that these cells are able to produce and respond to plasminogen activators.…”